We heard that if trained, your dog will use an electric toothbrush (in our case, battery-operated). Since we have single-handedly funded our Vet's office Christmas party on more than one occasion, we thought it would be worth the try.
I started by using my electric toothbrush around them. They were quite interested in it. Every now and then I'd stick it down toward them and they'd tray to grab at it. Baxter seemed particularly interested; Bella wanted it but was freaked out by the splashing it created. We forged ahead and picked up a kid's toothbrush because it had a small head. Corgis tend to have tight lips so fitting anything larger in their mouth probably wouldn't work.
In this video, they get their first sample of doggy toothpaste. Again, Bella wanted it (or probably just didn't want Baxter to have it). You'll see her pacing back and forth behind Baxter, yapping all the way. I think Baxter is going to do this! Not so sure about Bella.